Human pathogenic bacterium induces actin phosphorylation to selectively regulate

描述（由申请人提供）：许多细菌病原体在进入/内化或在细胞间传播时利用宿主肌动蛋白细胞骨架。肌动蛋白细胞骨架在节肢动物载体中的病原利用尚未探索。利用肩关节硬蜱和嗜吞噬细胞无形体（人类粒细胞无形体病的病原体）作为感染模型，我首次提供了证据，证明了专性细胞内细菌如何利用肌动蛋白细胞骨架来控制节肢动物基因转录，从而为自己的利益服务。我的初步结果表明，嗜吞噬胞杆菌诱导蜱虫肌动蛋白磷酸化，随后改变单体/丝状（G/F）肌动蛋白比例。我还表明，A.吞噬细胞门诱导的肌动蛋白磷酸化依赖于Ixodes PAK1-PI3kinase信号传导。A.吞噬细胞诱导的肌动蛋白磷酸化导致核g -肌动蛋白和与RNA聚合酶II （RNAPII）相关的磷酸化肌动蛋白增加。细胞核中诱导的肌动蛋白磷酸化增强了tata -box-binding蛋白与RNAPII的结合，并导致salp16的选择性调控，salp16是嗜吞噬细胞芽胞杆菌存活的关键基因。本课题旨在探索salp16启动子在嗜吞噬细胞芽胞杆菌感染中选择性调控的机制。进一步的研究提出，以确定是否有任何细菌成分(s)或其他Ixodes转录激活因子(s)参与这种特定的基因调控。总的来说，这项研究可能为肌动蛋白磷酸化在宿主-病原体相互作用中的新作用提供证据，并提出干扰这种专性细胞内病原体的生命周期的新策略，也许还有其他具有医学重要性的立克次体相关微生物。

DESCRIPTION (provided by applicant): Many bacterial pathogens exploit host actin cytoskeleton either during entry/internalization or spread from cell to cell. Pathogen use of the actin cytoskeleton in arthropod vectors has not yet been explored. Using Ixodes scapularis ticks and Anaplasma phagocytophilum (the agent of human granulocytic anaplasmosis) as an infection model, I provide evidence for the first time to show how an obligate intracellular bacterium can exploit the actin cytoskeleton to control arthropod gene transcription for its own benefit. My preliminary results show that A. phagocytophilum induces the phosphorylation of tick actin and subsequently alters the ratio of monomeric/filamentous (G/F)-actin. I also show that A. phagocytophilum-induced actin phosphorylation is dependent on Ixodes PAK1-PI3kinase signaling. A. phagocytophilum-induced actin phosphorylation resulted in increased nuclear G-actin and phosphorylated actin that associated with RNA Polymerase II (RNAPII). Induced actin phosphorylation in the nucleus enhanced binding of TATA-box-binding-protein to RNAPII and caused the selective regulation of salp16, a gene crucial for A. phagocytophilum survival. This project proposal explores to identify the mechanism by which selective regulation of salp16 promoter is mediated upon A. phagocytophilum infection. Additional studies are proposed to identify whether any of the bacterial component(s) or other Ixodes transcriptional activator(s) are involved in this specific gene regulation. Collectively, this study may provide evidence for a novel role of actin phosphorylation during host- pathogen interaction and suggest new strategies to interfere with the life cycle of this obligate intracellular pathogen, and perhaps other Rickettsia-related microbes of medical importance. PUBLIC HEALTH RELEVANCE: In United States, Ixodes scapularis ticks transmit several human pathogens including A. phagocytophilum, the agent of human anaplasmosis. The molecular mechanisms that this bacterium uses to survive in its vector host are currently not understood. This project proposal provides evidence for a novel role of actin during host-pathogen interaction and suggests new strategies to interfere with the life cycle of this obligate intracellular pathogen, and perhaps other arthropod-borne microbes of medical importance.